51
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Michno K, Knight D, Campusano JM, Campussano JM, van de Hoef D, Boulianne GL. Intracellular calcium deficits in Drosophila cholinergic neurons expressing wild type or FAD-mutant presenilin. PLoS One 2009; 4:e6904. [PMID: 19730737 PMCID: PMC2733141 DOI: 10.1371/journal.pone.0006904] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2009] [Accepted: 08/01/2009] [Indexed: 01/07/2023] Open
Abstract
Much of our current understanding about neurodegenerative diseases can be attributed to the study of inherited forms of these disorders. For example, mutations in the presenilin 1 and 2 genes have been linked to early onset familial forms of Alzheimer's disease (FAD). Using the Drosophila central nervous system as a model we have investigated the role of presenilin in one of the earliest cellular defects associated with Alzheimer's disease, intracellular calcium deregulation. We show that expression of either wild type or FAD-mutant presenilin in Drosophila CNS neurons has no impact on resting calcium levels but does give rise to deficits in intracellular calcium stores. Furthermore, we show that a loss-of-function mutation in calmodulin, a key regulator of intracellular calcium, can suppress presenilin-induced deficits in calcium stores. Our data support a model whereby presenilin plays a role in regulating intracellular calcium stores and demonstrate that Drosophila can be used to study the link between presenilin and calcium deregulation.
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Affiliation(s)
- Kinga Michno
- Program in Developmental and Stem Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
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52
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Yu JT, Chang RCC, Tan L. Calcium dysregulation in Alzheimer's disease: from mechanisms to therapeutic opportunities. Prog Neurobiol 2009; 89:240-55. [PMID: 19664678 DOI: 10.1016/j.pneurobio.2009.07.009] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2009] [Revised: 07/28/2009] [Accepted: 07/31/2009] [Indexed: 11/28/2022]
Abstract
Calcium is involved in many facets of neuronal physiology, including activity, growth and differentiation, synaptic plasticity, and learning and memory, as well as pathophysiology, including necrosis, apoptosis, and degeneration. Though disturbances in calcium homeostasis in cells from Alzheimer's disease (AD) patients have been observed for many years, much more attention was focused on amyloid-beta (Abeta) and tau as key causative factors for the disease. Nevertheless, increasing lines of evidence have recently reported that calcium dysregulation plays a central role in AD pathogenesis. Systemic calcium changes accompany almost the whole brain pathology process that is observed in AD, including synaptic dysfunction, mitochondrial dysfunction, presenilins mutation, Abeta production and Tau phosphorylation. Given the early and ubiquitous involvement of calcium dysregulation in AD pathogenesis, it logically presents a variety of potential therapeutic targets for AD prevention and treatment, such as calcium channels in the plasma membrane, calcium channels in the endoplasmic reticulum membrane, Abeta-formed calcium channels, calcium-related proteins. The review aims to provide an overview of the current understanding of the molecular mechanisms involved in calcium dysregulation in AD, and an insight on how to exploit calcium regulation as therapeutic opportunities in AD.
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Affiliation(s)
- Jin-Tai Yu
- Department of Neurology, Qingdao Municipal Hospital, School of Medicine, Qingdao University, No. 5 Donghai Middle Road, Qingdao, Shandong Province 266071, China
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53
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Zampese E, Brunello L, Lissandron V, Pozzan T, Pizzo P, Fasolato C. P2‐195: Organelle‐targeted Ca2+ probes help to visualize store Ca2+ handling by wild‐type and mutant presenilin‐2. Alzheimers Dement 2009. [DOI: 10.1016/j.jalz.2009.04.507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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54
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Brunello L, Zampese E, Florean C, Pozzan T, Pizzo P, Fasolato C. Presenilin-2 dampens intracellular Ca2+ stores by increasing Ca2+ leakage and reducing Ca2+ uptake. J Cell Mol Med 2009; 13:3358-69. [PMID: 19382908 PMCID: PMC4516491 DOI: 10.1111/j.1582-4934.2009.00755.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We have previously shown that familial Alzheimer’s disease mutants of presenilin-2 (PS2) and, to a lesser extent, of presenilin-1 (PS1) lower the Ca2+ concentration of intracellular stores. We here examined the mechanism by which wild-type and mutant PS2 affect store Ca2+ handling. By using HeLa, SH-SY5Y and MEFs as model cells, and recombinant aequorins as Ca2+ probes, we show evidence that transient expression of either wild-type or mutant PS2 increases the passive Ca2+ leakage: both ryanodine- and IP3-receptors contribute to Ca2+ exit out of the ER, whereas the ribosome translocon complex is not involved. In SH-SY5Y cells and MEFs, wild-type and mutant PS2 potently reduce the uptake of Ca2+ inside the stores, an effect that can be counteracted by over-expression of SERCA-2B. On this line, in wild-type MEFs, lowering the endogenous level of PS2 by RNA interference, increases the Ca2+-loading capability of intracellular stores. Furthermore, we show that in PS double knockout MEFs, reduction of Ca2+ stores is mimicked by the expression of PS2-D366A, a loss-of-function mutant, uncleaved because also devoid of presenilinase activity but not by co-expression of the two catalytic active fragments of PS2. In summary, both physiological and increased levels of wild-type and mutant PS2 reduce the Ca2+ uptake by intracellular stores. To exert this newly described function, PS2 needs to be in its full-length form, even if it can subsequently be cleaved.
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Affiliation(s)
- Lucia Brunello
- Department of Biomedical Sciences, University of Padova, Padova, Italy
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55
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Celsi F, Pizzo P, Brini M, Leo S, Fotino C, Pinton P, Rizzuto R. Mitochondria, calcium and cell death: a deadly triad in neurodegeneration. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2009; 1787:335-44. [PMID: 19268425 DOI: 10.1016/j.bbabio.2009.02.021] [Citation(s) in RCA: 219] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 02/23/2009] [Accepted: 02/24/2009] [Indexed: 12/17/2022]
Abstract
Mitochondrial Ca(2+) accumulation is a tightly controlled process, in turn regulating functions as diverse as aerobic metabolism and induction of cell death. The link between Ca(2+) (dys)regulation, mitochondria and cellular derangement is particularly evident in neurodegenerative disorders, in which genetic models and environmental factors allowed to identify common traits in the pathogenic routes. We will here summarize: i) the current view of mechanisms and functions of mitochondrial Ca(2+) homeostasis, ii) the basic principles of organelle Ca(2+) transport, iii) the role of Ca(2+) in neuronal cell death, and iv) the new information on the pathogenesis of Alzheimer's, Huntington's and Parkinson's diseases, highlighting the role of Ca(2+) and mitochondria.
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Affiliation(s)
- Fulvio Celsi
- Department of Experimental and Diagnostic Medicine, Interdisciplinary Center for the Study of Inflammation, Italy
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56
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Cheung KH, Shineman D, Müller M, Cárdenas C, Mei L, Yang J, Tomita T, Iwatsubo T, Lee VMY, Foskett JK. Mechanism of Ca2+ disruption in Alzheimer's disease by presenilin regulation of InsP3 receptor channel gating. Neuron 2008; 58:871-83. [PMID: 18579078 DOI: 10.1016/j.neuron.2008.04.015] [Citation(s) in RCA: 359] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 02/05/2008] [Accepted: 04/16/2008] [Indexed: 01/24/2023]
Abstract
Mutations in presenilins (PS) are the major cause of familial Alzheimer's disease (FAD) and have been associated with calcium (Ca2+) signaling abnormalities. Here, we demonstrate that FAD mutant PS1 (M146L)and PS2 (N141I) interact with the inositol 1,4,5-trisphosphate receptor (InsP3R) Ca2+ release channel and exert profound stimulatory effects on its gating activity in response to saturating and suboptimal levels of InsP3. These interactions result in exaggerated cellular Ca2+ signaling in response to agonist stimulation as well as enhanced low-level Ca2+signaling in unstimulated cells. Parallel studies in InsP3R-expressing and -deficient cells revealed that enhanced Ca2+ release from the endoplasmic reticulum as a result of the specific interaction of PS1-M146L with the InsP3R stimulates amyloid beta processing,an important feature of AD pathology. These observations provide molecular insights into the "Ca2+ dysregulation" hypothesis of AD pathogenesis and suggest novel targets for therapeutic intervention.
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Affiliation(s)
- King-Ho Cheung
- Department of Physiology, University of Pennsylvania, Philadelphia, PA 19104, USA
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57
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P4‐203: Full‐length and not mature presenilin 2 increases the leakage of intracellular calcium stores: Specific mechanisms aand targets. Alzheimers Dement 2008. [DOI: 10.1016/j.jalz.2008.05.2271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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58
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Hayrapetyan V, Rybalchenko V, Rybalchenko N, Koulen P. The N-terminus of presenilin-2 increases single channel activity of brain ryanodine receptors through direct protein-protein interaction. Cell Calcium 2008; 44:507-18. [PMID: 18440065 DOI: 10.1016/j.ceca.2008.03.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Revised: 03/06/2008] [Accepted: 03/11/2008] [Indexed: 01/17/2023]
Abstract
Presenilin-1 (PS1) and presenilin-2 (PS2) form the catalytic core in gamma-secretase complexes and mutations in these proteins result in aberrant cleavage of amyloid precursor protein leading to accumulation of the beta-amyloid in the brain of familial Alzheimer Disease patients. PS2 possesses a hydrophilic cytoplasmic N-terminal domain (PS2 NTF1-87) dispensable for gamma-secretase activity with physiological functions yet to be determined. The effects of this soluble 87 amino acid fragment of mouse PS2 on single channel activity of mouse brain ryanodine receptors (RyR) were determined. PS2 NTF1-87 application to the cytoplasmic side of the RyR significantly increased single channel activity by favoring higher sublevel openings. The Ca(2+) activation and desensitization ranges for RyRs were unchanged. We demonstrate facilitation of RyR gating by PS2 NTF1-87, which might represent a general mechanism of RyR regulation by presenilins potentially prone to be affected by mutations or external stimuli contributing to the development of neurodegenerative diseases.
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Affiliation(s)
- Volodya Hayrapetyan
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107-2699, USA
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59
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Lopez JR, Lyckman A, Oddo S, Laferla FM, Querfurth HW, Shtifman A. Increased intraneuronal resting [Ca2+] in adult Alzheimer's disease mice. J Neurochem 2007; 105:262-71. [PMID: 18021291 DOI: 10.1111/j.1471-4159.2007.05135.x] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Neurodegeneration in Alzheimer's disease (AD) has been linked to intracellular accumulation of misfolded proteins and dysregulation of intracellular Ca2+. In the current work, we determined the contribution of specific Ca2+ pathways to an alteration in Ca2+ homeostasis in primary cortical neurons from an adult triple transgenic (3xTg-AD) mouse model of AD that exhibits intraneuronal accumulation of beta-amyloid proteins. Resting free Ca2+ concentration ([Ca2+](i)), as measured with Ca2+-selective microelectrodes, was greatly elevated in neurons from 3xTg-AD and APP(SWE) mouse strains when compared with their respective non-transgenic neurons, while there was no alteration in the resting membrane potential. In the absence of the extracellular Ca2+, the [Ca2+](i) returned to near normal levels in 3xTg-AD neurons, demonstrating that extracellular Ca2+contributed to elevated [Ca2+](i). Application of nifedipine, or a non-L-type channel blocker, SKF-96365, partially reduced [Ca2+](i). Blocking the ryanodine receptors, with ryanodine or FLA-365 had no effect, suggesting that these channels do not contribute to the elevated [Ca2+](i). Conversely, inhibition of inositol trisphosphate receptors with xestospongin C produced a partial reduction in [Ca2+](i). These results demonstrate that an elevation in resting [Ca2+](i), contributed by aberrant Ca2+entry and release pathways, should be considered a major component of the abnormal Ca2+ homeostasis associated with AD.
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Affiliation(s)
- José R Lopez
- Department of Anesthesia, Brigham & Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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60
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Bojarski L, Herms J, Kuznicki J. Calcium dysregulation in Alzheimer's disease. Neurochem Int 2007; 52:621-33. [PMID: 18035450 DOI: 10.1016/j.neuint.2007.10.002] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2007] [Revised: 09/12/2007] [Accepted: 10/01/2007] [Indexed: 12/21/2022]
Abstract
Alzheimer disease (AD) is the most common form of adult dementia. Its pathological hallmarks are synaptic degeneration, deposition of amyloid plaques and neurofibrillary tangles, leading to neuronal loss. A few hypotheses have been proposed to explain AD pathogenesis. The beta-amyloid (Abeta) and hyperphosphorylated tau hypotheses suggest that these proteins are the main players in AD development. Another hypothesis proposes that the dysregulation of calcium homeostasis may be a key factor in accelerating other pathological changes. Although Abeta and tau have been extensively studied, recently published data provide a growing body of evidence supporting the critical role of calcium signalling in AD. For example, presenilins, which are mutated in familial cases of AD, were demonstrated to form low conductance calcium channels in the ER and elevated cytosolic calcium concentration increases amyloid generation. Moreover, memantine, an antagonist of the NMDA-calcium channel receptor, has been found to have a beneficial effect for AD patients offering novel possibilities for a calcium signalling targeted therapy of AD. This review underscores the growing importance of calcium ions in AD development and focuses on the relevant aspects of calcium homeostasis.
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Affiliation(s)
- Lukasz Bojarski
- International Institute of Molecular and Cell Biology, 4 Ks. Trojdena Street, 02-109 Warsaw, Poland
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61
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Cowburn RF, Popescu BO, Ankarcrona M, Dehvari N, Cedazo-Minguez A. Presenilin-mediated signal transduction. Physiol Behav 2007; 92:93-7. [PMID: 17568632 DOI: 10.1016/j.physbeh.2007.05.053] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Presenilin proteins, mutated forms of which cause early onset familial Alzheimer's disease, are capable of modulating various cell signal transduction pathways, the most extensively studied of which has been intracellular calcium signalling. Disease causing presenilin mutations can potentiate inositol(1,4,5)trisphosphate (InsP3) mediated endoplasmic reticulum release due to calcium overload in this organelle, as well as attenuate capacitative calcium entry. Our own studies have shown a novel function for presenilins that involves regulation of acetylcholine muscarinic receptor-stimulated phospholipase C upstream of InsP3 regulated calcium release. This article reviews the mechanisms by which presenilins modulate intracellular calcium signalling and the role that deregulated calcium homeostasis could play in the pathogenesis of Alzheimer's disease.
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Affiliation(s)
- Richard F Cowburn
- Karolinska Institutet, Department of Neurobiology, Care Sciences and Society, KI-Alzheimer's Disease Research Center, Novum, plan 5, S-141 57 Huddinge, Sweden.
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62
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Giacomello M, Drago I, Pizzo P, Pozzan T. Mitochondrial Ca2+ as a key regulator of cell life and death. Cell Death Differ 2007; 14:1267-74. [PMID: 17431419 DOI: 10.1038/sj.cdd.4402147] [Citation(s) in RCA: 192] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Mitochondrial Ca(2+) homeostasis is today at the center of wide interest in the scientific community because of its role both in the modulation of numerous physiological responses and because of its involvement in cell death. In this review, we briefly summarize a few basic features of mitochondrial Ca(2+) handling in vitro and within living cells, and its involvement in the modulation of Ca(2+)-dependent signaling. We then discuss the role of mitochondrial Ca(2+) in the control of apoptotic death, focusing in particular on the effects of pro- and anti-apoptotic proteins of the Bcl-2 family. Finally, the potential involvement of Ca(2+) and mitochondria in the development of two diseases, Ullrich muscular dystrophy and familial Alzheimer's disease, is briefly discussed.
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Affiliation(s)
- M Giacomello
- Department of Biomedical Sciences and CNR Institute of Neurosciences, University of Padua, Viale G Colombo 3, Padua, Italy
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63
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Uberti D, Ferrari-Toninelli G, Bonini SA, Sarnico I, Benarese M, Pizzi M, Benussi L, Ghidoni R, Binetti G, Spano P, Facchetti F, Memo M. Blockade of the tumor necrosis factor-related apoptosis inducing ligand death receptor DR5 prevents beta-amyloid neurotoxicity. Neuropsychopharmacology 2007; 32:872-80. [PMID: 16936710 DOI: 10.1038/sj.npp.1301185] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
We originally suggested that inhibition of tumor necrosis factor-related apoptosis inducing ligand (TRAIL) death pathway could be taken into consideration as a potential therapeutic strategy for Alzheimer's disease (AD). However, because the critical role of TRAIL in immune surveillance, the neutralization of TRAIL protein by an antibody to prevent its binding to death receptors is definitely a risky approach. Here, we demonstrated that the blockade of the TRAIL death receptor DR5 with a specific antibody completely prevented amyloid beta peptide (A beta) neurotoxicity in both neuronal cell line and primary cortical neurons. DR5 was demonstrated to be a key factor in TRAIL death pathway. In fact, whereas TRAIL expression was enhanced dose-dependently by concentrations of beta amyloid ranging from 10 nM to 1 microM, only the highest toxic dose of A beta (25 microM) induced the increased expression of DR5 and neuronal cell death. In addition, the increased expression of DR5 receptor after beta amyloid treatment was sustained by p53 transcriptional activity, as demonstrated by the data showing that the p53 inhibitor Pifithrin alpha prevented both beta amyloid-induced DR5 induction and cell death. These data suggest a sequential activation of p53 and DR5 upon beta amyloid exposure. Further insight into the key role of DR5 in AD was suggested by data showing a significant increase of DR5 receptor in cortical slices of AD brain. Thus, these findings may give intracellular TRAIL pathway a role in AD pathophysiology, making DR5 receptor a possible candidate as a pharmacological target.
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Affiliation(s)
- Daniela Uberti
- Department of Biomedical Sciences and Biotechnologies, University of Brescia Medical School, Brescia, Italy.
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64
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P3–393: Familial Alzheimer's disease presenilin mutants reduce calcium levels of intracellular stores. A critical reevaluation of the “calcium overload” hypothesis. Alzheimers Dement 2006. [DOI: 10.1016/j.jalz.2006.05.1663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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65
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Zatti G, Burgo A, Giacomello M, Barbiero L, Ghidoni R, Sinigaglia G, Florean C, Bagnoli S, Binetti G, Sorbi S, Pizzo P, Fasolato C. Presenilin mutations linked to familial Alzheimer's disease reduce endoplasmic reticulum and Golgi apparatus calcium levels. Cell Calcium 2006; 39:539-50. [PMID: 16620965 DOI: 10.1016/j.ceca.2006.03.002] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 02/25/2006] [Accepted: 03/03/2006] [Indexed: 11/23/2022]
Abstract
Presenilin-1 and -2 (PS1 and PS2) mutations, the major cause of familial Alzheimer's disease (FAD), have been causally implicated in the pathogenesis of neuronal cell death through a perturbation of cellular Ca(2+) homeostasis. We have recently shown that, at variance with previous suggestions obtained in cells expressing other FAD-linked PS mutations, PS2-M239I and PS2-T122R cause a reduction and not an increase in cytosolic Ca(2+) rises induced by Ca(2+) release from stores. In this contribution we have used different cell models: human fibroblasts from controls and FAD patients, cell lines (SH-SY5Y, HeLa, HEK293, MEFs) and rat primary neurons expressing a number of PS mutations, e.g. P117L, M146L, L286V, and A246E in PS1 and M239I, T122R, and N141I in PS2. The effects of FAD-linked PS mutations on cytosolic Ca(2+) changes have been monitored either by using fura-2 or recombinant cytosolic aequorin as the probe. Independently of the cell model or the employed probe, the cytosolic Ca(2+) increases, caused by agonist stimulation or full store depletion by drug treatment, were reduced or unchanged in cells expressing the PS mutations. Using aequorins, targeted to the endoplasmic reticulum or the Golgi apparatus, we here show that FAD-linked PS mutants lower the Ca(2+) content of intracellular stores. The phenomenon was most prominent in cells expressing PS2 mutants, and was observed also in cells expressing the non-pathogenic, "loss-of-function" PS2-D366A mutation. Taken as a whole, our findings, while confirming the capability of presenilins to modify Ca(2+) homeostasis, suggest a re-evaluation of the "Ca(2+) overload" hypothesis in AD and a new working hypothesis is presented.
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Affiliation(s)
- Giancarlo Zatti
- Department of Biomedical Sciences, University of Padua, Italy
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66
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Ghidoni R, Benussi L, Paterlini A, Missale C, Usardi A, Rossi R, Barbiero L, Spano P, Binetti G. Presenilin 2 mutations alter cystatin C trafficking in mouse primary neurons. Neurobiol Aging 2006; 28:371-6. [PMID: 16545890 DOI: 10.1016/j.neurobiolaging.2006.01.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2005] [Revised: 12/30/2005] [Accepted: 01/21/2006] [Indexed: 10/24/2022]
Abstract
Mutations in the presenilin genes account for the majority of familial Alzheimer disease (FAD) cases. In the present report we demonstrated that the FAD-linked presenilin 2 mutations (PS2 M239I and T122R) alter cystatin C trafficking in mouse primary neurons reducing secretion of its glycosylated form. These mutations showed a different impact on cystatin C: PS2 T122R had a much stronger effect determining a dramatic intracellular accumulation of cystatin C (native and glycosylated), followed by a reduction in the secretion of both forms. Several experimental evidences suggest that cystatin C exerts a protective role in the brain and favors stem cells proliferation. Confocal imaging showed that the effect of PS2 T122R mutation was a massive recruitment of cystatin C into the neuronal processes, in the presence of an intact cytoskeletal structure. The consequent reduction in the cystatin C extracellular levels might result in a failure of neuroregeneration. Understanding the interplay of PS2 and cystatin C in the pathogenesis of AD might highlight new therapeutic prospective.
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Affiliation(s)
- Roberta Ghidoni
- NeuroBioGen Lab-Memory Clinic, IRCCS Centro S. Giovanni di Dio-FBF, AFaR, Brescia, Italy
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67
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Oh YS, Turner RJ. Effect of gamma-secretase inhibitors on muscarinic receptor-mediated calcium signaling in human salivary epithelial cells. Am J Physiol Cell Physiol 2006; 291:C76-82. [PMID: 16467403 DOI: 10.1152/ajpcell.00508.2005] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Altered intracellular Ca(2+) signaling has been observed in cells derived from Alzheimer's disease patients, and a possible link between gamma-secretase activity and the content of intracellular Ca(2+) stores has been suggested. To test this hypothesis we studied the effects of several gamma-secretase inhibitors on muscarinic receptor-mediated intracellular calcium release in the human salivary gland cell line HSG. Although several inhibitors in the peptide aldehyde class partially blocked carbachol-induced Ca(2+) transients, these effects did not appear to be due to gamma-secretase inhibition, and overall we found no evidence that inhibition of gamma-secretase activity had any significant effect on agonist-induced intracellular calcium release in HSG cells. In complementary experiments with presenilin-null cells we found that the reconstitution of gamma-secretase activity by transfection with wild-type presenilin 1 likewise had no significant effect on thapsigargin-induced Ca(2+) release. In a test of the specific hypothesis that the level of APP intracellular domain (AICD), the intracellular fragment of the beta-amyloid precursor protein (APP) resulting from gamma-secretase cleavage, can modulate the Ca(2+) content of the endoplasmic reticulum, we were unable to demonstrate any effect of APP small interfering RNA on the magnitude of carbachol-induced intracellular calcium release in HSG cells. Together our data cast considerable doubt on the hypothesis that there is a direct link between gamma-secretase activity and the content of intracellular Ca(2+) stores.
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Affiliation(s)
- Young S Oh
- Membrane Biology Section, Gene Therapy and Therapeutics Branch, National Institute of Dental and Craniofacial Research, Bldg 10, Rm. 1A01, GTTB, Bethesda, MD 20892, USA
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68
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Paschen W, Mengesdorf T. Cellular abnormalities linked to endoplasmic reticulum dysfunction in cerebrovascular disease—therapeutic potential. Pharmacol Ther 2005; 108:362-75. [PMID: 16140387 DOI: 10.1016/j.pharmthera.2005.05.008] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2005] [Accepted: 05/26/2005] [Indexed: 01/20/2023]
Abstract
Unfolded proteins accumulate in the lumen of the endoplasmic reticulum (ER) as part of the cellular response to cerebral hypoxia/ischemia and also to the overexpression of the mutant genes responsible for familial forms of degenerative diseases such as Alzheimer's disease, Parkinson's disease, Huntington's disease, amyothrophic lateral sclerosis, and Huntington's disease, as well as other disorders that are caused by an expanded CAG repeat. This accumulation arises from an imbalance between the load of proteins that need to be folded and processed in the ER lumen and the ER folding/processing capacity. To withstand such potentially lethal conditions, stress responses are activated that includes the shutdown of translation to reduce the ER work load and the activation of the expression of genes coding for proteins involved in the folding and processing reactions, to increase folding/processing capacity. In transient cerebral ischemia, ER stress-induced suppression of protein synthesis is believed to be too severe to permit sufficient activation of the genetic arm of the ER stress response. Mutations associated with Alzheimer's disease down-regulate the ER stress response and make cells more vulnerable to conditions associated with ER stress. When the functioning of the ER is severely impaired and affected cells can no longer withstand these stressful conditions, programmed cell death is induced, including a mitochondria-driven apoptotic pathway. Raising the resistance of cells to conditions that interfere with ER functions and activating the degradation and refolding of unfolded proteins accumulated in the ER lumen are possible strategies for blocking the pathological process leading to cell death at an early stage.
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Affiliation(s)
- Wulf Paschen
- Multidisciplinary Neuroprotection Laboratories, Duke University Medical Center, Department of Anesthesiology, 132 Sands Building, Research Drive, Durham, NC 27710, USA.
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69
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Smith IF, Green KN, LaFerla FM. Calcium dysregulation in Alzheimer's disease: Recent advances gained from genetically modified animals. Cell Calcium 2005; 38:427-37. [PMID: 16125228 DOI: 10.1016/j.ceca.2005.06.021] [Citation(s) in RCA: 103] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 06/28/2005] [Indexed: 10/25/2022]
Abstract
Alzheimer's disease is a progressive and irreversible neurodegenerative disorder that leads to cognitive, memory and behavioural impairments. Two decades of research have implicated disturbances of intracellular calcium homeostasis as playing a proximal pathological role in the neurodegeneration associated with Alzheimer's disease. A large preponderance of evidence has been gained from the use of a diverse range of cell lines. Whilst useful in understanding the principal mechanism of neurotoxicity associated with Alzheimer's disease, technical differences, such as cell type or even the form of amyloid-beta used often underlie conflicting results. In this review, we discuss recent contributions that transgenic technology has brought to this field. For example, the triple transgenic mouse model of Alzheimer's disease has implicated intraneuronal accumulation of the amyloid-beta peptide as an initiating factor in synaptic dysfunction and behavioural deficits. Importantly, this synaptic dysfunction occurs prior to cell loss or extracellular amyloid plaque accumulation. The cause of synaptic dysfunction is unknown but it is likely that amyloid-beta and its ability to disrupt intracellular calcium homeostasis plays a key role in this process.
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Affiliation(s)
- Ian F Smith
- Department of Neurobiology and Behavior, University of California, 1109 Gillespie Neuroscience Building, Irvine CA 92697-4545, USA
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70
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Paschen W, Mengesdorf T. Endoplasmic reticulum stress response and neurodegeneration. Cell Calcium 2005; 38:409-15. [PMID: 16087231 DOI: 10.1016/j.ceca.2005.06.019] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2005] [Accepted: 06/28/2005] [Indexed: 11/18/2022]
Abstract
The endoplasmic reticulum (ER) is a subcellular compartment playing a central role in calcium storage and signaling. Disturbances of ER calcium homeostasis constitute a severe form of stress interfering with central functions of this structure including the folding and processing of newly synthesized membrane and secretory proteins. Blocking the folding and processing reactions results in the accumulation of unfolded proteins forming potentially toxic aggregates. To restore ER functioning, specific stress responses are activated one of which is the unfolded protein response (UPR). UPR is characterized by a shutdown of global protein synthesis and activation of expression of genes coding for ER-resident proteins that are involved in the folding and processing reactions. ER calcium homeostasis is therefore inevitably associated with major cellular functions, including gene transcription and translation. ER calcium homeostasis und ER functions are believed to be impaired in various degenerative diseases of the brain including Alzheimer's, Parkinson's and Huntington's disease, and amyotrophic lateral sclerosis. ER functioning has also been shown to be disturbed in acute pathological states of the brain such as ischemia and trauma, which have been identified as risk factors for the development of degenerative diseases. This implies that there are common underlying pathomechanisms. This review will summarize new observations suggesting that impairment of ER functioning may be a common denominator of pathological processes resulting in neuronal cell injury in acute disorders and degenerative diseases of the brain.
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Affiliation(s)
- Wulf Paschen
- Multidisciplinary Neuroprotection Research Laboratories, Department of Anesthesiology, Duke University Medical Center, 132 Sands Building, Research Drive, Durham, NC 27710, USA.
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71
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Lessard CB, Lussier MP, Cayouette S, Bourque G, Boulay G. The overexpression of presenilin2 and Alzheimer's-disease-linked presenilin2 variants influences TRPC6-enhanced Ca2+ entry into HEK293 cells. Cell Signal 2005; 17:437-45. [PMID: 15601622 DOI: 10.1016/j.cellsig.2004.09.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Accepted: 09/07/2004] [Indexed: 12/31/2022]
Abstract
Mutations in the presenilin (PS) genes are linked to the development of early-onset Alzheimer's disease by a gain-of-function mechanism that alters proteolytic processing of the amyloid precursor protein (APP). Recent work indicates that Alzheimer's-disease-linked mutations in presenilin1 and presenilin2 attenuate calcium entry and augment calcium release from the endoplasmic reticulum (ER) in different cell types. However, the regulatory mechanisms underlying the altered profile of Ca(2+) signaling are unknown. The present study investigated the influence of two familial Alzheimer's-disease-linked presenilin2 variants (N141I and M239V) and a loss-of-function presenilin2 mutant (D263A) on the activity of the transient receptor potential canonical (TRPC)6 Ca(2+) entry channel. We show that transient coexpression of Alzheimer's-disease-linked presenilin2 mutants and TRPC6 in human embryonic kidney (HEK) 293T cells abolished agonist-induced TRPC6 activation without affecting agonist-induced endogenous Ca(2+) entry. The inhibitory effect of presenilin2 and the Alzheimer's-disease-linked presenilin2 variants was not due to an increase in amyloid beta-peptides in the medium. Despite the strong negative effect of the presenilin2 and Alzheimer's-disease-linked presenilin2 variants on agonist-induced TRPC6 activation, conformational coupling between inositol 1,4,5-trisphosphate receptor type 3 (IP(3)R3) and TRPC6 was unaffected. In cells coexpressing presenilin2 or the FAD-linked presenilin2 variants, Ca(2+) entry through TRPC6 could still be induced by direct activation of TRPC6 with 1-oleoyl-2-acetyl-sn-glycerol (OAG). Furthermore, transient coexpression of a loss-of-function PS2 mutant and TRPC6 in HEK293T cells enhanced angiotensin II (AngII)- and OAG-induced Ca(2+) entry. These results clearly indicate that presenilin2 influences TRPC6-mediated Ca(2+) entry into HEK293 cells.
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Affiliation(s)
- Christian B Lessard
- Department of Pharmacology, Faculty of Medicine, Université de Sherbrooke, 3001, 12e avenue Nord, Sherbrooke, Quebec, Canada J1H 5N4
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Giacomello M, Barbiero L, Zatti G, Squitti R, Binetti G, Pozzan T, Fasolato C, Ghidoni R, Pizzo P. Reduction of Ca2+ stores and capacitative Ca2+ entry is associated with the familial Alzheimer's disease presenilin-2 T122R mutation and anticipates the onset of dementia. Neurobiol Dis 2005; 18:638-48. [PMID: 15755689 DOI: 10.1016/j.nbd.2004.10.016] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2004] [Revised: 10/04/2004] [Accepted: 10/26/2004] [Indexed: 11/17/2022] Open
Abstract
Mutations in the presenilin genes PS1 and PS2, the major cause of familial Alzheimer's disease (FAD), are associated with alterations in Ca2+ signalling. In contrast to the majority of FAD-linked PS1 mutations, which cause an overload of intracellular Ca2+ pools, the FAD-linked PS2 mutation M239I reduces Ca2+ release from intracellular stores [Zatti, G., Ghidoni, R., Barbiero, L., Binetti, G., Pozzan, T., Fasolato, C., Pizzo, P., 2004. The presenilin 2 M239I mutation associated with Familial Alzheimer's Disease reduces Ca2+ release from intracellular stores. Neurobiol. Dis. 15/2, 269-278]. We here show that in human FAD fibroblasts another PS2 mutation (T122R) reduces both Ca2+ release and capacitative Ca2+ entry. The observation, done in two monozygotic twins, is of note since only one of the subjects showed overt signs of disease at the time of biopsy whereas the other one developed the disease 3 years later. This finding indicates that Ca2+ dysregulation anticipates the onset of dementia. A similar Ca2+ alteration occurred in HeLa and HEK293 cells transiently expressing PS2-T122R. Based on these data, the "Ca2+ overload" hypothesis in AD pathogenesis is here discussed and reformulated.
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Affiliation(s)
- Marta Giacomello
- Department of Biomedical Sciences, University of Padova, Via G. Colombo, 3, 35121 Padova, Italy
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Takuma K, Yan SS, Stern DM, Yamada K. Mitochondrial Dysfunction, Endoplasmic Reticulum Stress, and Apoptosis in Alzheimer’s Disease. J Pharmacol Sci 2005; 97:312-6. [PMID: 15750290 DOI: 10.1254/jphs.cpj04006x] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
Alzheimer's disease (AD) is the most common neurodegenerative disorder of late life characterized by insidious, chronic, and progressive memory impairment in association with the accumulation of senile plaques, neurofibrillary tangles, and massive loss of neurons. Apoptosis is believed to be an important contributor to progression and pathology of neurodegeneration in AD. There is considerable evidence that amyloid beta-peptide, a major component of senile plaques, has the capacity to activate intracellular apoptosis pathways leading to neuronal cell death. AD-related mutations in genes coding presenilins are also shown to cause neuronal apoptosis, by directly and indirectly regulating apoptotic signaling cascades. Recent evidence suggests that two intrinsic pathways, mitochondrial dysfunction and endoplasmic reticulum stress, are central in the execution of apoptosis in AD. This review summarizes recent progress of research in this field focused on the molecular mechanisms involved in neuronal apoptosis mediated by organelle dysfunction.
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Affiliation(s)
- Kazuhiro Takuma
- Laboratory of Neuropsychopharmacology, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa.
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